Needle roller for the fibrillation of a splittable plastics film

ABSTRACT

The invention relates to the fibrillation of plastics films. A needle roller to that purpose is described in which at least two needle combs are attached on or in the roller surface at mutually equal distances, which combs each consist of a row of needles adjacently arranged in a support and provided with torpedo-shaped points lying on one line and parallel to the roller axis, each needle having a diameter of 10 - 75 Mu m and reaching beyond the support over a length of maximum four times the diameter of the needle.

United States Patent [1 1 Klaase 1 July 24, 1973 NEEDLE ROLLER FOR THE FIBRILLATION [56] References Cited OF A SPLITTABLE PLASTICS FILM UNITED STATES PATENTS [75] Inventor: Petrus Theodorus Antonius Klaase, 3,565,308 2/1971 Slack 225/97 Voorburg, Netherlands 3,460,416 8/1969 Gilbert 225/97 X 3,536,238 10 1970 l t al. 2 97 [73] Assignee: Nederlandse Organisatie' Voor I wama e 2 5/ gzigr z ig: ggszsz azfi Primary Examiner-Frank T. Yost Nifierhem Handel En vukeer The AttorneyBrumbaugh, Free, Graves & Donohue Hague, Netherlands [57] ABSTRACT [.22] Filed: Sept' 1971 The invention relates to the fibrillation of lastics films.

P [21] Appl. No.: 182,380 A needle roller to that purpose is described in which at least two needle combs are attached on or in the roller surface at mutually equal distances, which combs each [3-0] Forelgn Apphcafion Pnomy Data consist of a row of needles adjacently arranged in a sup- Oct. 8, I970 Netherlands 7014809 p and Provided i p h p points y g on one line and parallel to the roller axis, each needle hav- [52] US. Cl 225/97, 83/660, 225/93 mg a diameter of 10 75 m and reaching beyond the [51] Int. Cl. 1/20, B26f 3/02 pp over a length of maximum four times the diam [58] Field of Search 225/97, 93, l, 2; etc. of the needle 83/2, 660; 28/DlG. l; 264/DIG. 8

1 Claim, 2 Drawing Figures PAIENIEDJ 3.747. 817

INVENTOR.

BY X444 5 NEEDLE ROLLER FOR THE FIBRILLATION OF A SPLITTABLE PLASTICS FILM The invention relates to a needle roller for the fibrillation of a splittable plastics film.

Such a needle roller is known in the art.

The split fibres manufactured with the aid of it can, on a limited scale, serve as a substitute for natural fibres and are applied as a miltifilament; in an appropriate way they can also be used as a material for coarse fabrics.

It has also been tried to find an application in the field of spun yarns by manufacturing split fibres with a slight diameter required for i.a., textile.

Relatively fine fibres can be manufactured by greatly increasing the relative speed of the needle roller in respect of that of the plastics film.

At increasing velocity of splitting the number of ruptures of individual filaments increases to a great extent, however, which results in a considerable decrease in the tensile strength of the yarn obtained. Moreover, the loose fibre ends occurring in the event of rupture, cause, in contrast with for example staple fibres, difficulties in further processing (i.a., weaving and knitting).

Now, the invention enables checking rupture, thus removing the restrictions described above.

Surprisingly it was found that upon application of needles that have a' very small diameterand a very small active length with respect to the needles in the needle roller known in the art, very fine split fibres can be manufactured, when contrary to the expectation hardly any rupture occurs.

The needle roller according to the invention is characterized in that itis provided with at least two needle combs attached on or in the roller surface at mutually equal distances and each consisting of a row of needles adjacently arranged in a support, and provided with torpedo-shaped points lying on one line and parallel to the roller axis, each needle having a diameter of IO 75 am and reaching beyond the su'pportover a length of maximum four tir'nes the diameter of the needle.

The so-called micro needles preferably have a diameter of 20 50 um and can be made of any appropriate hard or hardened metal, of graphite whiskers, silicium carbide whiskers and similar hard materials having a great abrasion resistance. Advantageously the micro needles are made of wolfram, however.

The torpedo-shaped points on these needles have a height equal to approximately the diameter of the needle.

Besides that as a result of the surprising find hardly any rupture occurs, with the aid of the micro needles split fibres can be manufactured that have the diameter, width and narrow width distribution that give the textile product a desirable grip" the undesirable glitter moreover being completely absent.

Upon application of the needle roller according to the invention now cutting the split film can advantageously be carried out before the fibrillation stage.

EXAMPLE I In a fibrillating device known in the art on the surface of a roller, parallel to the roller axis and at mutually equal distances six rows of micro needles are provided.

The micro needles had been made of wolfram with a thickness of am. The protruding point length was abt. 100 m.

The point-to-point distance of the needles in each comb amounted to 100 am.

With this needle roller a split film of polypropylene was fibrillated.

A fibrillate was obtained with a fine, uninterrupted net structure, whose substantially uniform fibre width amounted to abt. 30 am. The fibres had a soft grip and displayed no glitter. The strength of the yarn obtained amounted to 39 g/tex. The same split flim was also fibrillated with the customary needle roller into an average fineness that was comparable with that obtained according to the invention. The strength of this product amounted to 8.5 g/tex. The strength of the yarn according to the invention that is abt. 4.5 times greater must be attributed to the absence of broken filaments.

EXAMPLE II On to the surface-of the roller of example I at mutually equal distances and parallel to the roller axis now two rows of micro needles were provided.

It was found that with them a similar result could be obtained. For the yarn of this fibrillate even a strength of abt. 50 g/tex was measured.

In all cases the film velocity can be equal to that with the customary techniques.

Though in the examples a film of polypropylene is mentioned, it stands to reason that every splittable plastics film is eligible.

The invention will be further elucidated below with reference to a drawing, in which by way of example an embodiment is shown.

In it gives FIG. 1 a perspective view of a needle roller with needle combs;

Even square fibres with a diameter of spun filaments I were found to be realizable.

The great number of needles per cm. comb length also enables, with a view to yarn production, effectively fibrillating very narrow strips (width abt. 1 mm). This is not possible with the needle rollers with the conventional of population of needles because the mutual needle distances are also in the order of 1 mm, causing the narrow strips between two adjacent needles to tilt. For

this reason it is necessary to carry out, after the fibrillating stage, cutting into narrow strips.

FIG. 2 part of a needle comb on a strongly enlarged scale.

In FIG. 1 by 1 a roller is indicated, in the surface of which six recesses 2, regularly distributed over the roller periphery, are provided. In each recess a needle comb 3 is inserted and clamped in a way known in the art. Such a needle comb, of which in FIG. 2 a part is shown on a stongly enlarged scale, consists of a holder 4, in which in a known way needles 5 are inserted. Each needle has a diameter 8 of i0 am and protrudes above upper surface 6 of holder 4 over a distance 7, which maximal is equal to four times diameter 8 of needle 5. Each needle Shas a torpedo-shaped point, whose length 9 is approminately equal to diameter 8 of the needle.

Fixing a needle comb 3 into a recess 2 of roller 1 enables displacementinto a direction parallel to as well as perpendicular to the roller axis. As a result needle combs 3 can be adjusted such that in fibrillating an optimal result is reached.

being attached on or in said roller surface with said needles in respective combs in circumferential alignment, each needle (a) being made of tungsten, (b) having a stem diameter of 10-75 microns, (c) protruding beyond the roller surface by a maximum length of four times said stem diameter, and (d) being provided with a paraboloid-shaped point, said point having a height approximately equal to said stem diameter. 

1. Apparatus for fibrillation of a splittable plastic film, having a roller provided with needle combs, each comb having a row of needles adjacently arranged, in a support, along a line parallel to the roller axis, said combs being attached on or in the roller surface at mutually equal distances and protruding beyond the support and the roller surface, characterized in that: at least two needle combs are provided on said roller, each comb having a row of needles, the stems of which are equally spaced apart, said needle combs being attached on or in said roller surface with said needles in respective combs in circumferential alignment, each needle (a) being made of tungsten, (b) having a stem diameter of 10-75 microns, (c) protruding beyond the roller surface by a maximum length of four times said stem diameter, and (d) being provided with a paraboloid-shaped point, said point having a height approximately equal to said stem diameter. 